"on the first floor"
Translation:في ٱلْطّابِق اَلْأَوَّل
I don't think they would use على with building's floor.
In some dialects they might use this preposition to mean "to go to" but this is not how it works in MSA. On the other hand, we cannot coincide the English prepositions and their meanings with the Arabic ones and their meanings and work; The two serve different purposes and often they differ in translations.
Google Translator is not that good. It is beneficial for little things in Arabic but it often scrambles things with more complicated structure, or when a word in Arabic can have more than one meaning. That's why I use other means to translate sometimes (specially technical and scientific words) from and into Arabic and English. Mainly I use www.almaany.com - It does not translate phrases but only word to word but it has better explanations and definitions sometimes more than Google does.
Prepositions are also a source for confusion for Arabs themselves nowadays too. Not many people would think about it, but just as an example, the famous تصبح على خير for Good night is actually wrong, and the correct one is تصبح بخير - This is because you do not wake up one morning UPON a condition of feeling good (على) but you wake up in the morning INTO a condition of feeling good (بـ). Yet, many people don't realize this fact and might even see it weird to use another preposition.